1. Field of the Invention
The present invention relates to a package substrate processing method of dividing a package substrate into a plurality of individual package devices along a plurality of crossing division lines, the package substrate being composed of an electrode plate having the division lines formed on the front side for partitioning a plurality of regions where the package devices are respectively provided and a synthetic resin layer formed on the back side of the electrode plate for molding the package devices.
2. Description of the Related Art
In a semiconductor device fabrication process, a plurality of crossing division lines are formed on the front side of a substantially disk-shaped semiconductor wafer to thereby partition a plurality of regions where a plurality of devices such as ICs and LSIs are respectively formed. The semiconductor wafer is cut along the division lines to thereby obtain the individual devices. Each device thus obtained is packaged to be widely used in electric equipment such as a mobile phone and a personal computer.
A further reduction in size and weight of such electric equipment is desired and there has been developed a packaging technique capable of reducing the size of a semiconductor device package, called Chip Size Package (CSP). As one of the CSP techniques, a packaging technique called Quad Flat Non-lead Package (QFN) has been put into practical use. This packaging technique called QFN is such that a plurality of devices are arranged like a matrix on an electrode plate such as a copper plate so as to be partitioned by a plurality of division lines, the electrode plate having a plurality of connection terminals corresponding to the connection terminals of the devices. Further, the devices are molded with resin from the back side to thereby form a resin layer for integrating the electrode plate and the devices, thus forming a CSP substrate (package substrate). This package substrate is cut along the division lines to obtain the individual package devices (chip size packages) divided from each other.
In general, cutting of the package substrate is performed by a cutting apparatus having a cutting blade. This cutting apparatus includes a jig having a plurality of crossing escape grooves respectively corresponding to the division lines for allowing the escape of the cutting edge of the cutting blade and a plurality of suction holes respectively formed in a plurality of regions partitioned by these escape grooves. This jig is set on a holding table and the package substrate is held on the jig under suction. In this condition, the cutting blade is rotated and the holding table is relatively moved along the division lines of the package substrate, thereby cutting the package substrate along the division lines to obtain the individual package devices divided from each other (see Japanese Patent Laid-open No. 2009-142992, for example).
However, the package substrate mentioned above has a warp because the electrode plate and the devices are integrated with the resin layer formed on the back side of the electrode plate. In dividing the package substrate having a warp into the individual package devices (chip size packages), there is a case that the package substrate cannot be held under suction on the holding table of the cutting apparatus. To solve this problem, there has been proposed a processing method including the steps of preliminarily dividing the package substrate into large parts to such an extent that the warp is dispersed and next dividing each of these large parts into the individual package devices (chip size packages) (see Japanese Patent Laid-open No. 2000-124161, for example).